Measuring Heart Rate Easier for Diagnosing Sleep Disorders

Researchers may have found an easier way for diagnosing sleep disorders. Standard sleep studies are involved, necessitating an overnight stay at a sleep center or hospital, while wearing electrodes on the chest and head. During a sleep study, monitors record a variety of bodily functions to help diagnose sleep disorders.
Scientists from Israel and Germany have discovered that simply measuring and recording heart rate -then analyzing the data as it relates to breathing and sleep patterns- might be an easier way to diagnose sleep disorders
Synchronization between heart rate and breathing occurs during certain stages of sleep. Measuring heart rate and breathing can yield important information about sleep duration and quality. During inhalation, the heart beat speeds up. Heart rate slows with exhalation. During REM (rapid eye movement) sleep, heart rate and breathing become more variable, as opposed to deep, steady sleep with regular breathing.
The study included data from 295 people from the European project SIESTA, spanning seven countries. Nearly half have sleep disorders. Study participants underwent normal sleep studies, including electrodes that monitor heart rate, brain waves, eye movement, and muscle activity. Next, the researchers analyzed heart rate only in 150 subjects, known to have sleep disorders. Using their own mathematical model, measuring heart rate and breathing synchronicity, yielded the same results found in the traditional sleep studies. They found that heart rate and breathing are not synchronous during REM sleep, but that heart rate and breathing synchronizes during light and deep sleep.
The researchers plan to continue their studies. They hope that easier diagnosis of sleep disorders will help in the diagnosis of cardiac disease, and treatment of heart failure. Monitoring heart rate and respirations to determine the presence of sleep disorders might also help athletes with optimal training.
Sleep disorders can lead to serious health complications. Making sleep disorders easier to diagnose could reduce traffic fatalities that occur from lack of sleep, heart attacks, obesity, depression and stroke.

What A Sleep Study Can Reveal About Fibromyalgia

Research engineers and sleep medicine specialists from two Michigan universities have joined technical and clinical hands to put innovative quantitative analysis, signal-processing technology and computer algorithms to work in the sleep lab. One of their recent findings is that a new approach to analyzing sleep fragmentation appears to distinguish fibromyalgia patients from healthy controls.
Joseph W. Burns, a research scientist and engineer at the Michigan Tech Research Institute (MTRI); Ronald D. Chervin, director of the University of Michigan’s Michael S. Aldrich Sleep Disorders Laboratory; and Leslie Crofford, director of the Center for the Advancement of Women’s Health at the University of Kentucky, report the results of their study in the current issue of the journal Sleep Medicine
MTRI, a freestanding research institute acquired by Michigan Tech in 2006 and based in Ann Arbor, specializes in remote sensors that collect data, and in signal processing, using algorithms or computer programs to analyze and correlate the information the sensors gather. MTRI has developed an ongoing collaboration with the University of Michigan’s sleep laboratory, one of the nation’s leading clinical and research centers specializing in sleep medicine.
This several-year collaboration provided MTRI’s first opportunities to apply quantitative analysis, remote sensing technology and computer algorithms to clinical challenges, said Burns. “In this case, our analyses of sleep stage dynamics suggest potential clinical relevance,” he noted. Newly explored measures of sleep fragmentation seem to correlate—at least in this study—with levels of pain reported by fibromyalgia patients.
Burns, who has a PhD in electrical engineering, finds that more and more of his research is taking a biomedical turn. He and his team are working with Chervin to use signal-processing technology to record and analyze the brain waves and biophysical responses of children and adults with a variety of sleep disorders. They hope it will help them better understand conventional sleep patterns, as well as diagnose and treat sleep disorders.
They presented the results of research related to assessment of sleep-disordered breathing and sleep fragmentation at Sleep 2008, an international sleep research conference, in Baltimore in June.
Patients who may have sleep disorders often undergo complicated and expensive tests in sleep laboratories, Chervin explained. These studies collect an assortment of biophysical data that reflect brain, cardiovascular and muscle activity throughout the night. Up to now, these data had to be analyzed manually by highly trained technicians.
“We are collaborating to find new ways to analyze routinely collected data in a way that will be meaningful to the patient’s health and will help us understand how sleep disorders affect brain functions,” he said.
Automated analysis of data potentially can provide improved assessments and reduce the cost of sleep studies, Burns noted. For example, MTRI and UM have developed an automated technique for assessing the severity of sleep-disordered breathing, using just two signals—brain waves and respiration—instead of the dozen or more signals typically needed for standard visual scoring of a sleep study.
“It may even become possible for people to take sleep tests—simpler and more effective than some of those currently available—at home where they can sleep in their own familiar bedrooms,” he suggested.
Both partners are reaping the benefits of the collaboration, Burns said. Not only can automated technology improve clinical research; what the MTRI scientists have learned about biomedical techniques such as brain mapping is informing their more traditional work on radar and optical sensing technology.

Women Who Sleep Less Than 8 Hours Live Longer

How much sleep is too much or too little? For women, researchers at the University of California, San Diego say that to live longer, the optimal number is less than 8 hours, and that 5.0 to 6.5 hours is ideal.

Eight hours is too much sleep for women

In the new study, a team of investigators evaluated data originally collected between 1995 and 1999 from 459 women ranging in age from 50 to 81. That study had indicated women who slept 6.5 to 7.5 hours per night had the best survival rates.
Now, 14 years later, the researchers took another look at the original group of women, of whom 444 could be identified for evaluation purposes. Eight-six women had died.
According to the study’s lead scientists, Daniel F. Kripke, MD, professor emeritus of psychiatry at UC San Diego School of Medicine, “when sleep was measured objectively, the best survival was observed among women who slept 5 to 6.5 hours. Women who slept less than five hours a night or more than 6.5 hours were less likely to be alive at the 14-year follow-up.”
The researchers also found that obstructive sleep apnea among older women did not predict an increased risk of death. Kripke noted that while sleep apnea may be associated with a greater risk of death among younger women, “it does not seem to carry a risk in the older age group, particularly for women.”
Countless studies have explored the optimal amount of sleep needed for various populations, from infants to the elderly. According to the National Sleep Foundation, there is no “magic number.” Visitors to the Foundation’s website will find that “not only do different age groups need different amounts of sleep, but sleep needs are also individual.”
That said, research shows that getting too little sleep is associated with many health concerns, including inhibited productivity, difficulty remembering and consolidating information, increased risk for motor vehicle accidents, increase in obesity, increased risk of diabetes and heart problems, and increased risk for psychiatric conditions. Some research also shows that too much sleep (generally considered more than 9 hours or more) is associated with an increased risk of illness and morbidity.
Are people losing sleep over worrying whether they are getting enough or too much sleep? According to Kripke, the results of this new study should provide some answers, at least for women who may worry about sleeping less than 8 hours. “This means that women who sleep as little as five to six-and-a-half hours have nothing to worry about since that amount of sleep is evidently consistent with excellent survival.”